The first image freezes a moving object by using a fast shutter speed, while the second object creates the illusion of depth by using a shallow depth of field.
The composition of both images are quite strong. The 4 walls of each of the photographs are clear of any distracting objects or unsightly amputations (i.e. cutting off of secondary objects) which is one of the most common mistakes photographers make especially when working within the framework of larger scenes (such as your first photograph). Paying attention to both primary and secondary objects is one of the achievements of great photographers and you’ve shown that you posses this ability as well.
I would have liked to see a little more layering in your first photograph though. The lighting makes the image appear a little flat. I think if you could have managed to put in a strong foreground element (such as the bushes to the left of the frame) you would have provided a strong sense of depth and more texture and details.
However, the dog photograph is very strong and contains great texture. What I also love about this image is your ability to control the color spectrum of the image and limit it to predominantly neutral tones. This has helped you organize and simplify the composition.